1. Field of the Invention
The invention relates to a method of transmitting and/or storing digitized, data-reduced audio signals. Such a method is known, for instance, from the European patent specification 290 581.
2. Description of the Related Art
In a bit rate-reduced encoding of audio signals that are already available in a digitized form, e.g., having a 48 kHz scanning frequency/16 bit resolution, utilization of psychoacoustic phenomena in the perception of audio signals is known from EP 290 581 in a way that the original bit rate is considerably reduced. Such methods carrying out transcoding from a higher to a lower bit rate are commonly known as source coding. They particularly utilize masking effects of the ear in the frequency and time domain. It is the object of these methods to not change, if possible, the audible quality which the audio signal has before transcoding (source coding) by reducing the bit rate (optimum transcoding).
In many applications, there is a limited data capacity available for transmission or storage. If this bit rate, which is made available, is insufficient, a further data reduction according to the principles of optimum transcoding leads to sometimes considerable interference, especially in the form of considerable sound distortions. This same interference, of course, also occurs if the source coding is not two-staged, but takes place in one step.
Furthermore, in a method of transmitting and/or storing digitized, data-reduced audio signals it is known (DE 36 29 434 Al) to let further encoding steps follow if, after encoding, a predetermined bit rate is exceeded (code overload), until the actual bit rate no longer exceeds the designated bit rate. That is, if code overload exists after a first encoding sep, further encoding steps can be employed. However, this approach does not always avoid a code overload with certainty.